# What's the use of tantalum resistors in audio circuits? [closed]

I've been looking at some "pro audio" sites and saw that tantalum resistors are often mentioned with claim that they somehow improve sound quality, but I've been unable to find any reasonable descriptions for discrete component operation that don't trip my audiophoolery alarm.

So is there any real need for them?

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• What is it in their characteristics that makes them so good? – Leon Heller Apr 1 '13 at 14:05
• @Leon Heller I don't know. I've managed to find a paper describing them, but they don't seem to be overly interesting to me. My gut feeling says that their use is in audio is for purely psychological reasons, but I thought I'd ask here before dismissing it. – AndrejaKo Apr 1 '13 at 14:09
• Nice setup for April 1 shenanigans. – The Photon Apr 1 '13 at 16:25
• Tantalum resistors are silly unless you use good quality flux capacitors too. The best kind are brought back from the future. Beware though, it is very hard to find real ones today. Most are fakes that don't work at all or develop tacheon leaks. – Olin Lathrop Apr 1 '13 at 17:38
• All resistors behave differently depending on direction of current flow (just as cables behave differently). It's difficult and expensive to tell if regular ones are the right way in, though, so special tantalum ones are used in critical audio circuits which exploit similar physical effects as tantalum caps. This makes it very easy to tell if they're in the right way. – helloworld922 Apr 1 '13 at 18:26

Tantalum resistors are more compatible with tantalum capacitors.

You can hear the difference on a clean sustained bass note, where, with other metal resistors, you can hear the electrons shuffling up and down across the galvanic potential between the two metals. With tantalum, the murmur of the electrons is much happier. They do not grumble and mutter as much with tantalum.

I think it has something to do with Fermi levels in the different metals. I found this link:
Oh dear, it seems I can't post an instant link (good idea, too). Here is the image I found.

You can see clearly the electron's path between the two metals is much noisier.

One must be careful, grabbing info off the web! For instance, in my graphic above, there are a lot of errors. There is something fishy about it. For one, the Fermi levels are wrong for a metal. Here is a corrected image:

In many countries, on April 1, there is a tradition of practical jokes and pranks. This was intended to be an April 1 joke answer. Please do not take any statements in this post seriously! bb

• That's what I feared. – AndrejaKo Apr 1 '13 at 14:13
• @Bobbi Bennett Is this your opinion or something that you have read. I'd be interested in a link if you have one. – Andy aka Apr 1 '13 at 14:29
• Very hard to believe. What does "more compatible" mean? Also, I've yet to see any "hear the difference" statements about these ephemera (fancy contacts, expensive cables, ...) ever turned into a "measure the difference" finding. – Scott Seidman Apr 1 '13 at 14:44
• @ScottSeidman, you have never heard an electron grumble?? – Bobbi Bennett Apr 1 '13 at 15:09
• Another reason for my wife to call me Sheldon ;) – Scott Seidman Apr 1 '13 at 15:27

I have been an Electrical Engineer in the Professional Audio world for more than 15 years, and have worked with engineers from 10+ different Pro-Audio companies. I have never, ever heard of Tantalum Resistors.

Must be more of an audiophile thing than pro audio.

• +1 4 years at IMAX (high-end movie theaters) in the sound-systems group and we never once bothered with TR's. TR's are for corrosive/moist environments where Ni-Cr isn't appropriate. – DrFriedParts Apr 1 '13 at 16:08
• 1st time I've heard of them and I've designed a few PAs and done countless mixing and mastering jobs on folks music. – Andy aka Apr 1 '13 at 16:22
• 1st time I've heard of them and I've been in the industry for almost 8 months – NickHalden Apr 1 '13 at 20:04

## No!

@BobbiBennet posted this picture as an explanation for using tantalum resistors with tantalum capacitors.

In the picture, a "Fermi-Level discontinuity" explanation is posited as the reason why Aluminum and Tantalum parts work poorly with each other (in comparison to Tantalum-Tantalum).

## First, the application...

1. You don't have tantalum wires connecting things so the problem should still manifest.
2. Tantalum resistors are extremely inert so they are great for use in corrosive or moist environments. That's why they exist. It's possible that replacing a corroded Ni-Cr resistor in an old audio-amp with a tantalum one results in noticeably better audio (depending on the circuit topology), which may be the origin of this audiophilia.
3. The electron velocities are so great in metals (and amplification factors so high in audio applications) that Johnson thermal noise will trump any noise created by the Seebeck effect (metal discontinuity) at audio frequencies.

## ...and now the physics.

1. Fermi levels don't work this way. When you join two dissimilar materials the Fermi-levels align. It's the band-levels that move in the band-theory of solids.
2. Solid conductors don't have a band-gap (that's what makes them a conductor!). In terms of Fermi energies, aligning the Fermi-levels of two conductors would result in no discontinuity since the electrons on both sides of the interface would be in the conduction band and could move freely across.

3. The "number of electrons" (presumably free electrons) on both sides of a Tantalum/Aluminum interface would be equal. Otherwise, they would just move to equalize the distribution.

• you don't have any of those tantalum wire for sale, do you? I think I desperately need some for my audiophillistonic project. But... would I have to get tantalum inductors as well as possibly tantalum vacuum tubes for best results? – angelatlarge Apr 1 '13 at 16:47
• Oh, and don't forget your 2-meter long $100 power cord with gold-plated contacts! Also, make sure to replace your wall outlet with the gold version. – DrFriedParts Apr 1 '13 at 17:43 • So, the fish bowls need to be on different shelves, so their surfaces line up? I -thought- there was something fishy in the graphic. Plus, I think those are semiconductor levels on the fishbowls, right? Electrons below the Fermi-levels? Anyway, happy April1. – Bobbi Bennett Apr 1 '13 at 17:45 • But this totally ignores the all-important audiophool effect. Electrons can tunnel to all sorts of unlikely places in the presence of a strong belief field. Of course the system must be oxygen-free for this to work, and the effect is proportional the square of the price. – Olin Lathrop Apr 1 '13 at 17:45 • The gold plated contacts guarantee a good connection with a$1500 spike suppressor – Scott Seidman Apr 1 '13 at 22:09

It said this on Angela Instruments website: -

"offering unparalleled resolving power and transparency with warmth and musicality. NO metal film or foil type resistor even comes close"

I don't believe a word of it - they appear to cost about £2.50 or \$4.00 each. Placibo effect is my estimate of their usefullness. How can a resistor have "transparent" performance yet also be "warm" (or possess qualities of "musicality") - see quote above

• The placebo effect is what I too expect to be their main purpose. – AndrejaKo Apr 1 '13 at 14:52
• Good find. Angela also says they're no longer manufactured, so those wishing to drink the KoolAid should act soon. – Scott Seidman Apr 1 '13 at 14:52
• OK I'm checking my bank balance right now...... – Andy aka Apr 1 '13 at 14:55
• These have the special property that after you buy them for that price, they do work. – Olin Lathrop Apr 1 '13 at 18:56
• @OlinLathrop I wish some chips would do this!!! – Andy aka Apr 2 '13 at 7:03